UPD78F9234MC-5A4-A Datasheet, PDF (201/419 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 11 SERIAL INTERFACE UART6
11.4.2 Asynchronous serial interface (UART) mode
In this mode, data of 1 byte is transmitted/received following a start bit, and a full-duplex operation can be
performed.
A dedicated UART baud rate generator is incorporated, so that communication can be executed at a wide range of
baud rates.
(1) Registers used
• Asynchronous serial interface operation mode register 6 (ASIM6)
• Asynchronous serial interface reception error status register 6 (ASIS6)
• Asynchronous serial interface transmission status register 6 (ASIF6)
• Clock selection register 6 (CKSR6)
• Baud rate generator control register 6 (BRGC6)
• Asynchronous serial interface control register 6 (ASICL6)
• Input switch control register (ISC)
• Port mode register 4 (PM4)
• Port register 4 (P4)
The basic procedure of setting an operation in the UART mode is as follows.
<1> Set the CKSR6 register (see Figure 11-8).
<2> Set the BRGC6 register (see Figure 11-9).
<3> Set bits 0 to 4 (ISRM6, SL6, CL6, PS60, PS61) of the ASIM6 register (see Figure 11-5).
<4> Set bits 0 and 1 (TXDLV6, DIR6) of the ASICL6 register (see Figure 11-10).
<5> Set bit 7 (POWER6) of the ASIM6 register to 1.
<6> Set bit 6 (TXE6) of the ASIM6 register to 1. → Transmission is enabled.
Set bit 5 (RXE6) of the ASIM6 register to 1. → Reception is enabled.
<7> Write data to transmit buffer register 6 (TXB6). → Data transmission is started.
Caution Take the relationship with the other party of communication into consideration when setting the
port mode register and port register. In order to avoid the generation of unintended start bits
(falling signals), set PM43 to 0 (output) after having set P43 to 1.
User’s Manual U17446EJ5V0UD
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